Found in a 90s Motorola documentation, this circuit makes it a PUT. This component is not very common today. The graph shows the performance of the circuit.
This circuit was obtained in a 1975 magazine, but it can be easily assembled using BC548...
This circuit was obtained from Dutch documentation from 1964. The components are of the time, but...
This simple charger was found in a 1980s documentation. The transistor may be the TIP42 with a...